Microcontroller with integrated interface enabling reading data randomly from serial flash memory
A microcontroller includes a microprocessor, a serial flash memory interface, and input/output (I/O) terminals for coupling the serial flash memory interface to external serial flash memory. The microprocessor is operable to generate instruction frames that trigger respective commands to read data from specified addresses in the external serial flash memory. The serial flash memory interface receives and processes the instruction frames, obtains the data contained in the specified addresses in the external serial flash memory regardless of whether the specified addresses are sequential or non-sequential, and provides the data for use by the microprocessor.
1. A microcontroller comprising:
a microprocessor;
a serial flash memory interface; and
input/output (I/O) terminals coupled to the serial flash memory interface, the I/O terminals configured to couple the serial flash memory interface to external serial flash memory;
wherein the microprocessor is operable to configure instruction frames to trigger respective commands with respect to addresses in the serial flash memory, and
wherein the serial flash memory interface includes a serial flash memory controller that is configured to launch, if data read commands are enabled in instruction frames configured by the microprocessor, one or more instruction frames to thereby enable a reading of addresses in the serial flash memory in accordance with addresses specified in the instruction frames configured by the microprocessor.
2. The microcontroller of claim 1 further including a system bus, wherein the serial flash memory controller includes a finite state machine that is operable to specify which data signals received from the serial flash memory are to be passed to the system bus.
3. The microcontroller of claim 2 wherein the serial flash memory controller further includes a shift register to serialize data signals received from the serial flash memory, and wherein the finite state machine is operable to provide control signals to the shift register, the control signals specifying which data signals are to be passed along to the system bus.
4. The microcontroller of claim 1 wherein each instruction frame configured by the microprocessor includes an instruction code indicative of an action to be triggered in the serial flash memory.
5. The microcontroller of claim 4 wherein each instruction frame configured by the microprocessor further includes one or more of an option code or a dummy cycle.
6. The microcontroller of claim 1 wherein the serial flash memory controller includes a plurality of configuration registers, and wherein the microprocessor is operable to configure an instruction frame by writing to the configuration registers.
7. The microcontroller of claim 6 wherein the plurality of configuration registers allows the serial flash memory controller to handle different types of vendor-dependent instruction frames.
8. The microcontroller of claim 6 wherein the plurality of configuration registers includes one or more of:
a clock register to configure a frequency, polarity or phase of a serial clock; or
an instruction register to configure an instruction code in an instruction frame.
9. The microcontroller of claim 1 wherein the serial flash memory interface includes cache memory and a cache memory controller,
wherein, if the microprocessor requests data of the serial flash memory and the requested data already is stored in the cache memory, the cache memory controller is operable to filter the request from the microprocessor and to return the requested data stored in the cache memory.
10. The microcontroller of claim 1 wherein the serial flash memory controller is configured to launch, if data read commands are enabled in sequential instruction frames configured by the microprocessor, one or more instruction frames to thereby enable a reading of addresses in the serial flash memory in accordance with addresses specified in the instruction frames enabling the data read commands regardless of whether or not the addresses specified in the instruction frames configured by the microprocessor are sequential.
11. The microcontroller of claim 1 wherein the serial flash memory controller includes a shift register operable to serialize data received from the serial flash memory.
12. The microcontroller of claim 1 wherein the serial flash memory controller includes a multiplexor operable to select data to be transmitted when transmission of an instruction frame is in progress.
13. The microcontroller of claim 12 wherein the serial flash memory controller further includes a shift register operable to serialize the data after selection by the multiplexor.
14. A method of a microcontroller accessing data from external serial flash memory, the method comprising:
configuring, by a microprocessor in the microcontroller, instruction frames that trigger respective commands with respect to addresses in the serial flash memory;
processing the instruction frames in a serial flash memory interface in the microcontroller; and
if data read commands are enabled by instruction frames configured by the microprocessor, launching by the serial flash memory interface one or more instruction frames to enable a reading of data from addresses in the serial flash memory in accordance with addresses specified in the instruction frames configured by the microprocessor.
15. The method of claim 14 further including:
obtaining, by way of the serial flash memory interface, the data stored in the specified addresses in the serial flash memory; and
providing the data for use by the microprocessor.
16. The method of claim 14 further including specifying, by the serial flash memory interface, which data signals received from the serial flash memory are to be passed to a microcontroller system bus.
17. The method of claim 16 further including:
receiving, in a shift register in the serial flash memory interface, data signals from the serial flash memory; and
providing control signals to the shift register, the control signals specifying which of the data signals are to be passed along to the microcontroller system bus.
18. The method of claim 14 further including configuring, by the microprocessor, an instruction frame by writing to one or more configuration registers in the serial flash memory interface.
19. The method of claim 18 wherein the one or more configuration registers allow the serial flash memory interface to handle each of a plurality of different types of vendor-dependent instruction frames.
20. The method of claim 14 further including:
receiving, in the serial flash memory interface, a request from the microprocessor for data of the serial flash memory; and
if the requested data is stored in cache memory in the serial flash memory interface, filtering the request and returning to the microprocessor the requested data stored in the cache memory.
21. The method of claim 14 wherein, if data read commands are enabled by instruction frames configured by the microprocessor, launching by the serial flash memory interface one or more instruction frames to enable a reading of data from addresses in the serial flash memory in accordance with addresses specified in the instruction frames enabling the data read commands regardless of whether or not the addresses specified in the instruction frames configured by the microprocessor are sequential.
22. A system comprising:
a microcontroller;
a serial flash memory external to the microcontroller,
the microcontroller comprising:
a microprocessor;
a serial flash memory interface; and
input/output (I/O) terminals coupled to the serial flash memory interface, the I/O terminals coupling the serial flash memory interface to the serial flash memory;
wherein the microprocessor is operable to configure instruction frames to trigger respective commands with respect to addresses in the serial flash memory, and
wherein the serial flash memory interface includes a serial flash memory controller that is configured to launch, if data read commands are enabled in instruction frames configured by the microprocessor, one or more instruction frames to thereby enable a reading of addresses in the serial flash memory in accordance with addresses specified in the instruction frames configured by the microprocessor.
23. The system of claim 22 wherein the serial flash memory controller is configured to launch, if data read commands are enabled in sequential instruction frames configured by the microprocessor, one or more instruction frames to thereby enable a reading of addresses in the serial flash memory in accordance with addresses specified in the instruction frames configured by the microprocessor regardless of whether or not the addresses specified in the instruction frames configured by the microprocessor are sequential.